If you find yourself wanting to replace an existing doorway with a wall, the bulk of the project can be accomplished in a long weekend. Changing a doorway into a solid wall is actually a fairly easy process.
Based on my research, the easy answer is no. Open cell spray foam performs better than closed cell, but neither is effective at blocking sound transfer. The qualities that make it an excellent thermal barrier also create disruptive resonance and its adhesion couples the wall elements together increasing noise transfer.
It's up to you to insulate the door by mounting insulating panels or placing foam panels into the door channels. Garage doors insulation will reduce the amount of heat or cold coming from the outside, but it may not be as much as you expect.
Spray foam is known as one of the best types of insulation to install to reduce noise. One reason why spray foam is considered the best in noise reduction is because it not only blocks out unwanted noise but keeps in good noise. When watching a movie, for instance, you want the sounds to be kept within that room.
Examine the Door's Finish
Hollow core doors are not often stained by manufacturers, except for veneer doors. If a wood door is stained, then it is more likely that the door is solid core than hollow core, particularly if the door is heavy. If the door is painted, then it is likely a hollow core door.
In general, an interior door in a residential house can hold between 45 to 100 pounds. An exterior door with robust hardware can withstand anywhere from 200 to 400 pounds.
Isn't foam used for soundproofing a room?” Unfortunately not. Foam doesn't stop a sound, it absorbs or reduces echo within the room.
Both open cell and closed cell foam are useful for vehicle soundproofing and insulation. Open cell foam absorbs sound, but closed cell foam is more durable. Both are great for insulation.
Cover walls with thick blankets, moving pads, tapestries, or quilts. Virtually any soft material will work, though thicker ones absorb more sound than thinner materials. If you don't mind adding an industrial look to the room, fasten sound-absorbing panels to the walls and, if necessary, the ceiling.
Fiberglass doors have some type of foam at their core, which gives them the opportunity to be extremely well-insulated and one of the best soundproof door options if the foam is high-density.
Hollow Core Doors: Pros & Cons
Despite their name, hollow core doors aren't completely hollow inside. They have a honeycomb cardboard interior that's wrapped by veneer or fiberboard.
Hollow core doors are the most commonly used interior door in mid-priced new homes. They are constructed with a thin layer of wood or fiberboard applied over a honeycombed cardboard or plastic core.
Exterior doors are almost always solid-core, because hollow-core doors are easy to damage and provide little security or insulation.
STC Rating of Spray Foam vs Rockwool
Of course, the higher the STC rating, the better. As you can see, from a purely acoustic insulation standpoint, rockwool outperforms both spray foam types by quite a lot.